Clutch



Feb. 26, 1929.

c. J. WHITACRE ET AL CLUTCH Filed May 20, 1926 2 Sheets-Sheet Feb. 26, 1929.

C. J. WHITACRE El' AL CLUTCH `Filed May 20. 1926 2 Sheets-Sheet 2 atenied Feb.v 26, 1929.

NITED STATES CLARENCE J. WHITACRE, OF FLINT, AND ALBERT MICHIGAN.

l C E s. GEISTERT, or DETROIT,

CLUTCH.

Application led May 20,

This invention relates to clutches, and is illustrated as embodied, in two modiications, in a single plate clutch and in a cone clutch', for an automobile.

This application is iiled as a continuation in part of our application for clutches led May 10, 1924, Serial No. .712313, and is intended to secure protection on the self lubricating clutch releasinglring.

An important object of tlETnvention-is to secure permanent lubrication of'. the clutch release or throw out bearing, and if desired of the clutch release lever fulcrum," by the use of a solid material of considerable hardness, so that it will wearpractically for the life of the clutch, and having a substantial.

`tensile strength so that it will stand up indelinitely under the shocks and jars received by an automobile clutch. Having this object in View, we arrange-the clutch release with aV throw out bearing part of solid lubricating material, preferably a heavy compressed and highly heated mixture of graphite and a bonding material, in the form of a iigid block.

If desired, the block may also beimpregnat-` ed with a heavy lubricating oil or grease.

In one desirable arrangement which is found in practice to be capable of withstanding the roughest kind of usage, the clutch throw out bearing comprises a metal enclosure for the above-described block of graphitic material, the block being supported by the enclosure and projecting from it at one side for engagement with a plane surface on an axially movable clutch releasing part.'

Other objects and features of the 1nven tion will be apparent from the following description of two illustrative embodiments shown in `the accompanying drawings, in which:

Figure 1 is la view, partly in side elevation i and partly in vertical section, of a plate clutch embodying the invention, with itsassociated parts;

Figure 2 is a horizontal section through part of the clutch, showing the clutch release lever;

Figure 3 is a clutch release lever, showing the clutch release bearing; l

Figure 4 is a rear elevation of the plateclutch;

Figure 5vis a side elevation, partly broken away, showing the invention embodied in a cone clutch; and

front elevation of part of the i926. serial No. 110,44.

Figure 6 is avertical section through the i cone clutch release bearing.

In Figures 1-4 the invention is shown embodied in a plate clutch arranged to connect the engine 10 and transmission 12 of an automobile. The clutch is enclosed in a housing 14, and comprises a fiywheel 16 on the crankshaft 18 of the engine, a vdriven plate 20 splined on a clutch shaft 22, and an annularplate or operating ring 24 rotating with the flywheel 16 but axially movable as is usual in a plate clutch. The iiywheel is formed with an outer flange 26 enclosing the above described parts and carrying anfvend pla-te 28 on which are fulcrumed a series of clutch operating levers 30. According to'onefeature of the present invention, each lever 30.has a slotted end embrae ing al pin 32 carried by a boss 34 on the ring 24, so that the levers move the ring positively fin both directions.

24 isnorinally forced toward the left ii`i"Figure-1,toengage the clutch, by a series or' coil springs 36,y e'aclr'of which is seated at one end in a socket in the ring 24, and encircles at its opposite end apart struck up from the endplate 28. The/levers 30 are connected by pivot pins 38 to a ring-40 having a plane rear face torbe engaged Yby the clutch release or throw out bearingfa'n anti-rattle Spring 42 for each lever being provided if desired. As shown in Figure'4 the spring 42 -may be coiled about pivot pin B'BTanTaricion l thereto, and may have an -end formed to extend alongthe lever 80 and engage the same to hold the lever ina7 predetermined position.

The ring is forced to the left Figure l) to'disengage the clutch, by a pedal-operated clutch release lever 44fulcrumed between its ends on a ball-ended post 46 by means of a metal enclosure or cup 48 fitting into an opening in the clutch-release lever and provided with a cover engaged by a take-up spring 50. The cup 48 contains af'socket member 52 of permanent solid lubricant such as the graphitic material described below.

According to an important featureof the invention, the clutch release lever 44 operates the ring 40 through a clutch release or throw out bearing comprising an annular metal enclosure or backing 54 having a flange 56 pivotally connected tothe forked end of lever 44 by means of pins 58. A guard may be provided if desired. This enclosure 54 'is provided with a rigmlarneilr r'ing 62 projecting from its side into engagement with the plane surface of the ring 40, and consisting of permanent solid graphite lubricant.

While it is not our intention to claim in this application the process of making the bearing ring 62, `it is to be recognized that vthis ring has certain desirable qualities which obviate the difficulties encountered in previous attempts to utilize such substances as graphite for permanent bearings, and which will be most `easily recognized in considering its method of manufacture.

Accordingly, to outline this method briefly,

it may be said that pure graphite, free from with benzine, which cuts the binder and causes it to co-act with each particle of graphite, the benzine being recovered by condensation while the mixture is heated at a low heat. The mixture, thus dried, is again ground and air-floated, the nelyalivided mixture thus secured being the raw material for manufacturing the clutch release bearing parts.

y This powdered mixture is heavily compressed, by hydraulic pressure, in molds giving it substantially the form shown in the drawings, and, after removal from-the molds, the rings so formed are heated about 400 hours at a. high temperaiture of approxi4 mately 2300O F. After being allowed to cool slowly, they are then boiled for from Li0 to 48 hours in heavy lubricating oil or grease, to impregnate them thoroughly.

The resulting bearing member 62 is a very hon'iogeneous mass of graphite, with sulficient binder or bonding material, impregnated with oil or grease, and with a tensile strength of approximately 10,000 pounds per square inch, and a hardness as measured with the scleroscope of from 30 to i0 degrees. W'hen run against a smooth steel surface, such as the ring 40, it operates without score ing or cutting and takes on an extremely smooth finish. It operates especially well at a unit pressure 'up to 130 pounds per square inch at 1000 R. P. M., and at correspondingly lower or higher pressures at other speeds. The wear under these circumstances is so small as to be barely detectable over a period of 100 hours at full load.

It will be seen that the above-described improved bearing member is supported in a novel manner so that, while graphitic solid compounds are usually so brittle and weak as not to be capable of use in an automobile, this particular member is stron g enough, and is so efficiently and completely backed and supported by the metal enclosure 54, as to be good for more than the normal life of the clutch in spite of the severe shocks and jars to which it is continually subjected, while there is practically no wear in ordinary use, on account of its substantial hardness and its having a smooth bearing surface of material which is itself an efficient lubricant.

In the embodiment shown in Figures 5 and 6, this material is used as the clutch release bearing for a cone clutch comprising a tlywheel 70, a cone 72, and a flange 74 having a plane front surface and which is forced to the right (Figure to disengage the clutch. The clutch release bearing comprises a metal enclosure or backing containing a block 78 of the above-described graphitic material projecting from its rear face into engagement with the flange 74, and pivotallyneonnected by pintles tolugs formed on a pedal-operated rock member 82. The annular enclosure 76 is in-the'formof a yoke having a central opening 84 for the clutch shaft 86. The annular block 78 is held by a wedge stamping 8S drawn upwardly by a small bolt 90.

Thilo twoillustrative embodiments of the invention have Abeen described in detail, it is not our intention to limit its scope to thosev particular embodiments, or otherwise than by the ,terms of the appended claims.

le claim:

l. A self lubricating thrust throw out bearing for'clutches composed of graphite carried by a suitable binder.

2. A clutch throw out bearing including graphite carried by a binder, the bearing having as characteristics, extreme hardness, great tensile strength and good heat conductivity. 3. A permanently lubricated clutch throw Vout bearing comprising, in combination, an

annular metal enclosure formed to vreceive operating connections from a clutch pedal, and an annular bearing block secured in and lsupported by said enclosure in such a manner as to luoject therefrom at one side, said block consisting of a heavily connnessed and highly healed mixture of graphite and a bonding material, the enclosure and block both having central openings for the clutch shaft.

4. A permanently lubricated automobile clutch throw out bearing comprising, incombination, a supporting enclosure having a central opening for the clutch shaft and arranged at opposite sides to be pivotally secured to connections from a clutch pedal, and

a bearing block of solidlubricating material containing Agraphite supported by and projecting from .one side ofthe enclosure and having a central opening for the clutch shaft, the solid material being of very substantial 5 hardness to wear very slowly and having a considerable tensile strength to withstand shocks and jars without breakage when used in an automobile.

5. In a clutch, a throw out bearing mount- 10 ed to receive intermittent axial thrusts and to resist relative rotary motion, said bearing composed of graphite and a. suitable binder, and having'as characteristics hardness, high tensile strength and good heat conductivity. 6. The invention defined b claim 5, said bearing being saturated with ubricant.

`In testimony whereof we aix our signatures.

CLARENCE J. WHITACRE. i ALBERT G. GEISTERT. 

